Safety valve



. D M NlCOLL SAFETY VALVE Filed Jan. 24 L925 2 Sheets-Sheet 1 @hwLL M M D. M NlCOLL SAFETY VALVE Filed Jan. 24. 1925 2 Sheets-$heet 2 [Ow 2 Z M Patented Aug. 31, 1926.

UNITED STATES DONALD MAGNICQLL', 0F GARDONALD, NEAR GLASGOW,

COCKBURNS LIMITED, OF COMPANY.

SCOTLAND, ASSIGNOR TO GARDONALID, NEAR GLASGOl/V, SCOTLAND, A BRITISH SAFETY VALVE.

Application filed January 24, {325, Serial No.

This invention relates to safety Valves in which an auxiliary member on the valve spindle serves to ensure an extra lift of the valve and permits reduction of the area of the valve opening.

An object of the invention is to provide a construction which obviates all liability of the auxiliary member to and yet ensures against excessive blow oil? of steam into the stoke-hold when the valve is open.

In the valve of the invention there is fixed to or formed integral with the valve spindle a solid diaphragm or auxiliary member having excessive clearance in an embracing annular shell, the underside of which diaphragm or member presents a substantial area subjectto upward steam prssure when the valve lifts. The excessive clearance ensures against all possibility of the diaphragm or member jamming.

To prevent the building up of pressure above the solid diaphragm or auxiliary member due to leakage when the valve is closed a. large outlet for leakage steam is provided beyond the diaphragm.

To prevent escape of an undue quantity of steam past the edge of the solid diaphragm and so to the outlet and thence into the stoke-hold when the valve is open, there is provided a loose intercepting member which may be normally in intercepting position and which may be in the form of an annulus loosely fitting the flange on the spindle which serves to seat the spring, the lower ed eqc of the intercepting member being eng geable with the upper edge of the said annular shell. i

The intercepting member may be nornially retained in closing position by gravity only or by spring pressure and may in addition he inturnciil or shouldered near its lower end to present an area exposed to downward steam pressure.

is the intercepting member is loose, if it should jam itself on the spindle flange when the valve lifts the only consequence of jamming would be that the intercepting member would also lift and permit the blow off or steam through the outlet.

iilternatively, the intercepting member may be constituted by the annular shell itself, the shell presenting an area exposed to upward pressure of steam which lifts the shell to cover the passage to the outlet.

4,509, and in Great Britain December 9, 1924.

In the accompanying drawings, Fig. 1 is a vertical section of part of a safety valve constructed in accordance with the inven tion; Figs. 2 and 3 are fragmentary sections showing modified constructions.

As shown in Fig. 1, there is formed integral with the valve spindle 1 a solid diaphragm or auxiliary member 2 having excessive clearance in an embracing annular shell 3, the underside of which diaphragm 2 presents a substantial area subjectto up ward steam pressure when the valve 41- lifts. The excessive clearance ensures against all possibility of the diaphragm 2 amming.

To prevent the building up of pressure above the diaphragm 2 due to leakage a large outlet 8 for leakage steam is provided.

To prevent escape of an undue quantity of steam past the edge of the solid diaphragm 2 and so to the outlet 8 and thence into the stoke-hold when the valve is open, there is provided a loose intercepting member 5 in the form of an annulus loosely fitting the flange 6 on the spindle which serves to seat the spring 7, the lower edge of the intercepting member 5 being engageable with the upper edge of the annular shell 3.

The intercepting member 5 is normally retained in closing position by gravity only and is inturned or shouldered near its lower end to present an area exposed to downward steam pressure.

As the intercepting member 5 is loose, if it should jam itself on the spindle flange 6 when the valve lifts the only consequence of jamming would be that the member 5 would also lift and permit the blow off of steam through the outlet.

In the modification shown in Fig. 2, the intercepting member 5 is urged towards normal or closing position by the pressure of a spring 9.

As shown in Fig. 3, the intercepting member is constituted by the annular shell 3, the shell presenting an area exposed to upward pressure of steam which on the opening of the valve lifts the shell to cover the passage to the outlet.

\Vhat I claim is 1. In a steam safety valve, in combination with a valve proper, a valve spindle having a springseating flange above said valve proper, an auxiliary member on said spindle intermediate said valve proper and said flange, said member presenting on its under side a large area to upward steam pressure, an annular shell embracing said member with large clearance, there being a large outlet beyond said shell and a loose annulus resting on said shell and surrounding said flange and serving in eonjunetioi'i with said flange, to restrict the flow of steam to said outlet when the valve is open but free to lift with said flange in the event of jamming of said flange and said annulus.

2. In a steam safety valve in combination with a valve proper, a valve spindle, an auxiliary member on said spindle above said said member, and a loose annulus of largerinternal diameter than said member, said annulus normally supported in a position surrounding said member and serving to restrict the flow of steam to said outlet when the valve is open but free to lift with said spindle in the event of its jamming on said member.

In testimony whereof I have signed my name to this specification.

' DONALD lvIAeNICOLL. 

